1. Technical Field
The present invention relates to liquid-ejecting heads having piezoelectric devices that cause a pressure change in pressure-generating chambers communicating with nozzle orifices and that include a piezoelectric layer and electrodes that apply a voltage to the piezoelectric layer, and also relates to liquid-ejecting apparatuses and piezoelectric devices.
2. Related Art
Among piezoelectric devices is one including a piezoelectric layer (piezoelectric film) formed of a piezoelectric material having an electromechanical conversion function, for example, a crystallized piezoelectric material, and two electrodes between which the piezoelectric layer is disposed. This type of piezoelectric device is provided on a liquid-ejecting head, for example, as an actuator that operates in a flexural vibration mode. A typical example of a liquid-ejecting head is an ink-jet recording head including a diaphragm that defines part of a pressure-generating chamber communicating with a nozzle orifice from which ink droplets are ejected and a piezoelectric device that deforms the diaphragm to pressurize ink in the pressure-generating chamber to eject ink droplets from the nozzle orifice.
The piezoelectric layer included in the piezoelectric device requires the use of a piezoelectric material with high piezoelectricity, a typical example of which is lead zirconate titanate (PZT) (see JP-A-2001-223404). From the viewpoint of environmental issues, on the other hand, there is a demand for a piezoelectric material with a lower lead content. Examples of lead-free piezoelectric materials include BiFeO3-based piezoelectric materials containing bismuth and iron, one specific example being a multiple oxide represented as a mixed crystal of bismuth manganate ferrate, such as Bi(Fe,Mn)O3, and barium titanate, such as BaTiO3 (see JP-A-2009-252789).
However, a piezoelectric layer formed of a mixed crystal of bismuth manganate ferrate and barium titanate has the problem of leakage current. This problem is not unique to liquid-ejecting heads such as ink-jet recording heads; other piezoelectric devices share the same problem.